The paper considers distributed applications where interactions between constituent services take place via messages in an asynchronous environment with unpredictable communication and processing delays; further, interacting parties are not required to be on- line at the same time. Message-oriented middleware (MoM) is commonly used for connecting such loosely coupled distributed applications. Despite loose coupling, many service interactions have temporal and message validation constraints. A failure to deliver a valid message within its time constraint could cause mutually conflicting views of an interaction (one party regarding it as timely whilst the other party regarding it as untimely) leading to application level inconsistencies. In a loosely coupled system, such inconsistencies could remain undetected for a long time, requiring costly application level recovery procedures. This paper describes how synchronisation support providing multilateral consistency guarantees can be provided using the underlying MoM to prevent inconsistencies from reaching application level.
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